Match transcript message weight to conversation text

The agent's in-transcript messages (the self-talk that renders between
markers) and mid-turn user prompts step up to font-medium, matching the
persisted conversation rows. Marker rows and their expanded details
keep their lighter treatment.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

desktop/src/features/chats/ui/ChatActivityTranscript.tsx

@@ -488,7 +488,7 @@ function ChatTranscriptMessageRow({
         {isUser ? (
           <Bubble side="right">
             <Markdown
-              className="min-w-0 [&_*]:text-primary-foreground [&_a]:text-primary-foreground [&_code]:bg-primary-foreground/15 [&_code]:text-primary-foreground"
+              className="min-w-0 font-medium [&_*]:text-primary-foreground [&_a]:text-primary-foreground [&_code]:bg-primary-foreground/15 [&_code]:text-primary-foreground"
               compact
               content={displayText || text || " "}
             />
@@ -496,7 +496,7 @@ function ChatTranscriptMessageRow({
         ) : (
           <Markdown
             agentAuthored
-            className="w-full max-w-none text-sm leading-6"
+            className="w-full max-w-none text-sm font-medium leading-6"
             content={displayText || text || " "}
           />
         )}